Flame retardant polycarbonate compositions containing polytetrafluoroethylene (PTFE) are known in the art. U.S. Pat. No. 4,391,935 discloses such compositions which also include certain salts. U.S. Pat. No. 3,294,871 discloses a process for producing molding compositions containing PTFE and a thermoplastic polymer entailing blending the thermoplastic polymer with a latex of the PTFE to produce a dispersed, substantially homogeneous mixture of the PTFE and a thermoplastic polymer and recovering the composition by removing the volatiles therefrom. Among the polymers polycarbonates are listed at col. 3, lines 6-8. The disclosed compositions are said to offer advantages in terms of impact strength, melt index, coefficient of friction, low water permeability and increased HDT.
U.S. Pat. No. 3,005,795 discloses compositions containing PTFE resin in a form of finely divided microfibrous and submicrofibrous particles. Polycarbonates are disclosed at col. 3, lines 18-19 as a suitable matrix. Improved moldability of PTFE resins is disclosed in U.S. Pat. No. 3,290,412 to result upon adding thereto of 10 to 40% of polycarbonates.
U.S. Pat. No. 3,723,373 discloses adding PTFE emulsion to polyethylene terephthalate for improved processability. French patent No. 1,412,767 addresses problems associated with the moldability of PTFE.
Lontz et al in Industrial and Engineering Chemistry, Vol. 44, No. 8 (1952) at page 1800 describes the general dispersion properties in film forming characteristics of PTFE. Coagulation of the dispersion by the addition of electrolytes or other solvents or by other means is also disclosed.
German published specification DE-OS No. 33 22 260 discloses PTFE co-precipitated with ABS and added to polycarbonate. Related technologies are disclosed in EP-OS. No. 0,154,138, which discloses a system entailing ABS and Teflon, DE-OS. No. 34 17 476 which discloses the system of polyamides and Teflon and DE-OS, No. 34 18 750 which concerns the system of ABS co-precipitated with PTFE. Also of relevance are DE-OS No. 34 20 002, DE-OS No. 34 22 862, DE-OS No. 35 12 638 (equivalent to EP-OS No. 0,174,493) DE-OS No. 29 48 439 and U.S. Pat. No. 4,208,489.
U.S. Pat. No. 3,940,455 discloses the incorporation of Teflon in elastomeric hydrocarbons by dissolving the elastomeric polymer in a solvent and incorporating the PTFE to form a suspension and subsequently co-precipitating both by mixing the suspension with a non-solvents. The co-precipitate is said to exhibit improved physical properties.